Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 966 · 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.🔮 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
2. 2.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
5. 5.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a magnet (d) white paper
7. 7.True or false: writing the message is a job for an adult. (a) True (b) False
8. 8.⚖️ 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) how dark the writing is (d) the kind of juice
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
10. 10.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
11. 11.True or false: ironing the paper is a job a child can do. (a) False (b) True
12. 12.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) yeast (d) white paper
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a magnet (d) lemon juice
15. 15.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
16. 16.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
17. 17.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) letting the paper dry
18. 18.True or false: plugging in the iron is a job a child can do. (a) True (b) False
19. 19.True or false: letting the paper dry is a job for an adult. (a) True (b) False
20. 20.🧺 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) yeast
21. 21.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) putting the iron away
23. 23.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
24. 24.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
25. 25.🔮 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
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) turmeric powder
27. 27.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) cutting the lemon
28. 28.True or false: reading the message is a job for an adult. (a) True (b) False
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
30. 30.⚖️ 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 measure it (c) we keep it the same
31. 31.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
34. 34.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
35. 35.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
36. 36.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
37. 37.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
38. 38.True or false: reading the message is a job a child can do. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
40. 40.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed

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