Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 816 · 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 needed for the secret lemon message? (a) a mirror (b) a magnet (c) a cotton bud (d) a battery cell
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
3. 3.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
4. 4.⚖️ 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
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) a mirror
6. 6.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
7. 7.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) cutting the lemon
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) white paper (d) lemon juice
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) white paper
10. 10.True or false: writing the message is a job for an adult. (a) True (b) False
11. 11.⚖️ 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) False (b) True
12. 12.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
13. 13.⚖️ 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 paper (c) the iron setting (d) the kind of juice
14. 14.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
16. 16.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) ironing the paper (d) plugging in the iron
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
18. 18.🍋 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) letting the paper dry
19. 19.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) putting the iron away (d) plugging in the iron
20. 20.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
22. 22.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
23. 23.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
24. 24.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a balloon (d) lemon juice
25. 25.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
26. 26.True or false: putting the iron away is a job a child can do. (a) True (b) False
27. 27.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
29. 29.⚖️ 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
30. 30.🍋 Which of these steps is a job a child can do? (a) reading the message (b) putting the iron away (c) ironing the paper (d) cutting the lemon
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the iron setting (c) how dark the writing is (d) the kind of juice
32. 32.⚖️ 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) True (b) False
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) yeast
34. 34.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
35. 35.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
36. 36.True or false: reading the message is a job for an adult. (a) False (b) True
37. 37.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
38. 38.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
39. 39.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) an adult with an iron (d) a mirror

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