Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 860 · 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.🧺 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) lemon juice
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
3. 3.True or false: cutting the lemon is a job for an adult. (a) False (b) True
4. 4.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
6. 6.⚖️ 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 same paper (c) how dark the writing is (d) the ironing time
7. 7.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
8. 8.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a small bowl (c) white paper (d) a cotton bud
10. 10.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the iron setting (c) the kind of juice (d) how dark the writing is
12. 12.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
13. 13.⚖️ 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
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
15. 15.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
18. 18.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) a small bowl
20. 20.⚖️ 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 keep it the same (c) we change it
21. 21.True or false: putting the iron away is a job a child can do. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
24. 24.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a magnet (d) lemon juice
26. 26.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
27. 27.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) reading the message (d) writing the message
28. 28.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) writing the message
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a small bowl (d) a mirror
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) writing the message
31. 31.⚖️ 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
32. 32.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) turmeric powder (d) an adult with an iron
35. 35.⚖️ 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 iron setting (c) the kind of juice
36. 36.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
37. 37.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
38. 38.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper
39. 39.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) white paper (c) a balloon (d) yeast
40. 40.⚖️ 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 measure it (c) we keep it the same

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids