Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 260 · 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.True or false: letting the paper dry is a job for an adult. (a) False (b) True
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the ironing time
3. 3.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) lemon juice (d) a cotton bud
5. 5.True or false: putting the iron away is a job a child can do. (a) True (b) False
6. 6.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) reading the message
7. 7.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) cutting the lemon (d) reading the message
8. 8.True or false: putting the iron away is a job for an adult. (a) False (b) True
9. 9.⚖️ 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 same paper (c) the kind of juice
10. 10.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
11. 11.True or false: plugging in the iron is a job for an adult. (a) False (b) True
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) an adult with an iron
13. 13.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
15. 15.⚖️ 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) True (b) False
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) yeast (d) a cotton bud
17. 17.⚖️ 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
18. 18.True or false: cutting the lemon is a job a child can do. (a) False (b) True
19. 19.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
20. 20.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
21. 21.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) putting the iron away
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) lemon juice (d) white paper
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
24. 24.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) how dark the writing is (d) the ironing time
27. 27.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
28. 28.⚖️ 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
29. 29.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) ironing the paper
30. 30.⚖️ 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 measure it (c) we keep it the same
31. 31.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
32. 32.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) a small bowl (d) turmeric powder
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
37. 37.⚖️ 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
38. 38.True or false: ironing the paper is a job a child can do. (a) True (b) False
39. 39.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
40. 40.True or false: white paper is needed for the secret lemon message. (a) False (b) True

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