Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 888 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
2. 2.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
4. 4.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
5. 5.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
6. 6.⚖️ 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 cotton bud (c) how dark the writing is (d) the kind of juice
7. 7.⚖️ 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 keep it the same (c) we change it
8. 8.⚖️ 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) True (b) False
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
10. 10.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a cotton bud (d) an adult with an iron
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) an adult with an iron (d) a small bowl
15. 15.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
16. 16.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
17. 17.True or false: white paper is needed for the secret lemon message. (a) False (b) True
18. 18.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same cotton bud (c) the ironing time (d) the same paper
20. 20.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
21. 21.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
22. 22.🛟 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
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
24. 24.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
25. 25.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a small bowl (c) a battery cell (d) turmeric powder
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a small bowl (d) yeast
27. 27.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) ironing the paper
28. 28.True or false: writing the message is a job a child can do. (a) True (b) False
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
30. 30.True or false: writing the message is a job for an adult. (a) True (b) False
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a balloon
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) lemon juice (d) a small bowl
34. 34.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
35. 35.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
36. 36.True or false: letting the paper dry is a job for an adult. (a) True (b) False
37. 37.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: plugging in the iron is a job for an adult. (a) True (b) False
40. 40.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed

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