Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 184 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
2. 2.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) cutting the lemon (d) reading the message
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.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
5. 5.⚖️ 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
6. 6.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) reading the message
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) yeast (d) lemon juice
8. 8.True or false: reading the message is a job a child can do. (a) False (b) True
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) a magnet
10. 10.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
12. 12.⚖️ 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 kind of juice (c) the ironing time (d) how dark the writing is
13. 13.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) writing the message
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
17. 17.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
19. 19.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a mirror (d) a cotton bud
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
23. 23.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
24. 24.True or false: letting the paper dry is a job for an adult. (a) False (b) True
25. 25.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
26. 26.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) yeast (c) a battery cell (d) a balloon
27. 27.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) plugging in the iron (d) letting the paper dry
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a magnet (d) a mirror
29. 29.⚖️ 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) False (b) True
30. 30.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
31. 31.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a balloon (d) an adult with an iron
34. 34.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) writing the message
35. 35.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the iron setting (d) the ironing time
37. 37.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
38. 38.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) yeast (d) a small bowl
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a battery cell (d) a cotton bud

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