Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 742 · 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? True or false: the iron setting is kept the same. (a) True (b) False
2. 2.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
3. 3.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
4. 4.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) putting the iron away
5. 5.🧺 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 magnet (d) a small bowl
6. 6.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
7. 7.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a balloon (d) a mirror
8. 8.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a battery cell (d) a cotton bud
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the iron setting (c) the ironing time (d) the kind of juice
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) a cotton bud (d) lemon juice
13. 13.True or false: putting the iron away is a job for an adult. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a mirror (d) a cotton bud
16. 16.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) putting the iron away (d) cutting the lemon
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a magnet (d) white paper
19. 19.True or false: letting the paper dry is a job for an adult. (a) True (b) False
20. 20.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) yeast (d) a magnet
21. 21.⚖️ 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
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
23. 23.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same cotton bud (d) the same paper
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
26. 26.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) yeast (d) white paper
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) an adult with an iron (d) lemon juice
29. 29.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
30. 30.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper
31. 31.True or false: yeast is needed for the secret lemon message. (a) True (b) False
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.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
34. 34.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
35. 35.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
36. 36.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a balloon
38. 38.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
40. 40.True or false: writing the message is a job for an adult. (a) True (b) False

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