Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 840 · 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.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
2. 2.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
3. 3.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
4. 4.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
5. 5.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) dipping the cotton bud (d) letting the paper dry
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
7. 7.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
8. 8.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) a small bowl (d) lemon juice
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
11. 11.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
12. 12.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) magnetic (d) physical
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
16. 16.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a balloon (d) a cotton bud
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a small bowl (d) turmeric powder
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) a cotton bud (d) lemon juice
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
21. 21.⚖️ 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) how dark the writing is (c) the iron setting (d) the same paper
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the iron setting (c) the ironing time (d) the kind of juice
23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a magnet (d) a cotton bud
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) white paper (d) a small bowl
28. 28.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
29. 29.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
30. 30.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
31. 31.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
32. 32.🛟 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
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
34. 34.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
37. 37.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
39. 39.⚖️ 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
40. 40.⚖️ 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

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