Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 986 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
2. 2.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) cutting the lemon (d) ironing the paper
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
7. 7.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
8. 8.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
9. 9.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same paper (c) the kind of juice (d) the ironing time
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) a small bowl (d) a mirror
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) an adult with an iron
17. 17.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) plugging in the iron
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
20. 20.True or false: cutting the lemon is a job a child can do. (a) True (b) False
21. 21.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
22. 22.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) writing the message
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a balloon (d) a small bowl
27. 27.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
29. 29.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
30. 30.True or false: yeast is needed for the secret lemon message. (a) False (b) True
31. 31.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) plugging in the iron (d) ironing the paper
33. 33.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) reading the message
34. 34.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) putting the iron away (d) ironing the paper
35. 35.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) yeast (d) a balloon
36. 36.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
37. 37.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) ironing the paper
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a small bowl (d) an adult with an iron
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) a cotton bud (d) a small bowl
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False

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