Invisible Ink Experiment Worksheet

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

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