Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 902 · 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 what we measure. (a) False (b) True
2. 2.True or false: plugging in the iron is a job a child can do. (a) True (b) False
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
4. 4.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) lemon juice (d) a small bowl
6. 6.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) a magnet (d) a small bowl
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.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
11. 11.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
12. 12.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) plugging in the iron
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.⚖️ 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
15. 15.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
17. 17.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a small bowl (d) an adult with an iron
21. 21.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) yeast (d) a small bowl
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a battery cell (d) an adult with an iron
24. 24.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
25. 25.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) yeast (d) lemon juice
27. 27.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) reading the message (d) writing the message
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) turmeric powder
29. 29.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) reading the message (d) plugging in the iron
30. 30.True or false: white paper is needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
32. 32.True or false: cutting the lemon is a job for an adult. (a) True (b) False
33. 33.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
34. 34.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
35. 35.True or false: letting the paper dry is a job for an adult. (a) True (b) False
36. 36.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) cutting the lemon
37. 37.⚖️ 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 measure it (c) we change it
38. 38.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
39. 39.⚖️ 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 same cotton bud (c) the iron setting (d) the kind of juice
40. 40.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it

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